1. Field of the Invention
The present invention relates to encoding of data to provide for robust error recovery due to data losses typically incurred during transmission of signals.
2. Art Background
A number of techniques exist for reconstructing lost data due to random errors that may occur during signal transmission or storage. However, these techniques cannot handle the loss of consecutive packets of data. Consecutive loss of packets of data is described in the art as burst error. Burst errors may result in a reconstructed signal with such a degraded quality that it is easily apparent to the end user. Additionally, compression methodologies used to facilitate high speed communications compound the signal degradation caused by burst errors, thus adding to the degradation of the reconstructed signal. Examples of burst error loss affecting transmitted and/or stored signals is seen in high definition television (xe2x80x9cHDTVxe2x80x9d) signals, mobile telecommunication applications, as well as video storage technologies including video disk and video cassette recorders (VCRs).
In one application, the advent of HDTV has led to television systems with a much higher resolution than the current standards proposed by the National Television Systems Committee (xe2x80x9cNTSCxe2x80x9d). Proposed HDTV signals are predominantly digital. Accordingly, when a color television signal is converted for digital use it is common that the luminance and chrominance signals are digitized using eight bits. Digital transmission of NTSC color television requires a nominal bit rate of about two hundred and sixteen megabits per second. The transmission rate is greater for HDTV which would nominally require about 1200 megabits per second. Such high transmission rates are well beyond the bandwidths supported by current wireless standards. Accordingly, an efficient compression methodology is required.
Compression methodologies also play an important role in mobile telecommunication applications. Typically, packets of data are communicated between remote terminals in mobile telecommunication applications. The limited number of transmission channels in mobile communications requires an effective compression methodology prior to the transmission of packets. A number of compression techniques are available to facilitate high transmission rates.
Adaptive Dynamic Range Coding (xe2x80x9cADRCxe2x80x9d) and Discrete Cosine Transform (xe2x80x9cDCTxe2x80x9d) Coding provide image compression techniques known in the art. Both techniques take advantage of the local correlation within an image to achieve a high compression ratio. However, an efficient compression algorithm can result in compounded error propagation because errors in an encoded signal are more prominent when subsequently decoded. This error multiplication can result in a degraded video image that is readily apparent to the user.
The present invention includes a system and method for encoding data by altering data of a rotation block by a rotation factor dependent on data of a key block. In one embodiment, the data includes compression parameters that are descriptive of compressed data. In one embodiment, data of the second block is altered by calculating a rotation factor from data of a first block and altering data of the second block in accordance with the rotation factor.
In another embodiment, the present invention includes a method for recovering data when there are data losses by determining candidate rotation values for full decoding data of the second block and selecting a rotation value from the candidate rotation values corresponding to the first block data.